The disclosure relates generally to antenna array sharing in a multi-operator radio node in a communications system, such as a macrocell radio, a small cell radio, remote radio heads (RRHs), etc., as examples. Such massive antenna array sharing allows such a communications system to support multiple operators.
Wireless communications is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, local area wireless services (e.g., so-called “wireless fidelity” or “WiFi” systems) and wide area wireless services are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Communications systems have been provided to transmit and/or distribute communications signals to wireless devices called “clients,” “client devices,” or “wireless client devices,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device. Example applications where communications systems can be used to provide or enhance coverage for wireless services include public safety, cellular telephony, wireless local access networks (LANs), location tracking, and medical telemetry inside buildings and over campuses. One approach to deploying a communications system involves the use of radio node/base station that transmits communications signals distributed over physical communications medium remote unit forming radio frequency (RF) antenna coverage areas, also referred to as “antenna coverage areas.” The remote units each contain or are configured to couple to one or more antennas configured to support the desired frequency(ies) of the radio node to provide the antenna coverage areas. Antenna coverage areas can have a radius in the range from a few meters up to twenty meters, as an example. Another example of a communications system includes radio nodes, such as base stations, that form cell radio access networks, wherein the radio nodes are configured to transmit communications signals wirelessly directly to client devices without being distributed through intermediate remote units.
For example, FIG. 1A is an example of a communications system 100 that includes a radio node 102 configured to support one or more service providers SP1-SPN, 104(1)-104(N) as signal sources (also known as “carriers” or “service operators”—e.g., mobile network operator (MNO)) and wireless client devices 106(1)-106(W). For example, the radio node 102 can be a component of a distributed antenna system (DAS) that is configured to distribute communications signal streams 108(1)-108(S) from the radio node 102 to the wireless client devices 106(1)-106(W) based on a downlink communications signal 110(1)-110(N) received from the service providers 104(1)-104(N). As another example, the radio node 102 may be a base station (eNodeB) that includes modem functionality. The communications signal streams 108(1)-108(N) are radiated through antennas 112 to the wireless client devices 106(1)-106(W) in communication range of the antennas 112. As another example, the radio node 102 in the communications system 100 in FIG. 1A can be a small cell radio access node (“small cell”) that is configured to support multiple service providers 104(1)-104(N) by distributing a communications signal stream 108(1)-108(S) for the multiple service providers 104(1)-104(N) based on respective communications signals 110(1)-110(N) received from respective evolved packet cores (EPC) network CN1-CNN of the service provider 104(1)-104(N) through interface connections. Small cells can support one or more service providers in different channels within a frequency band to avoid interference and reduced signal quality as a result. Secure communications tunnels are formed between the wireless client devices 106(1)-106(W) and the respective service provider 104(1)-104(N). Thus, in this example, the radio node 102 essentially appears as a single node (e.g., Evolved Node B (eNodeB) in 4G or gNodeB in 5G) to the service provider 104(1)-104(N). The issue with this approach (sometimes called MOCN) is that the capacity enabled by the channels of the “site operator,” which operates radio node 102, is divided between the service providers 104(1)-104(N). A better approach is where each service provider 104(1)-104(N) can use its own spectrum.
Massive Antenna Arrays (MAA) were introduced to enhance performance, in general, and in most cases in the case of a single service provider 104(1)-104(N). MAAs enhance performance by enabling techniques such as MU-MIMO and beamforming. A MAA includes a plurality of antenna elements that can support a number of users, support aggregated data rate, and increase the effective power with reduced interference. A MAA can be provided for each service provider SP1-SPN supported in a communications system. The communications system 100 can also be configured to support beamforming with a single MAA shared by multiple supported service providers SP1-SPN. For example, the antenna 112 in the communications system 100 in FIG. 1A can be a MAA 114 as shown in FIG. 1B. A MAA 114 contains a plurality of antenna elements 116(1)-116(E), for example sixty-four (64) antenna elements. Beamforming or spatial de-multiplexing is a signal processing technique used in wireless communications for directional signal transmission and/or reception. This is achieved by combining antenna elements in an antenna array in a way that signals at particular angles experience constructive interference while others experience destructive interference. Beamforming can be used at both the transmitting and receiving ends in order to achieve spatial selectivity. For example, the front end of 5G radio nodes, especially at frequencies above 2.5 GigaHertz (GHz) may include a MAA and supporting RF processing circuit elements.
In the communications system 100 in FIG. 1A, the size and number of antenna elements 116(1)-116(E) in the MAA 114 depends on the frequencies and spatial isolation to be supported by a site operator circuit 118 in the radio node 102. The site operator circuit 118 in FIG. 1A is configured to create multiple simultaneous signal beams (“beams”) 120(1)-120(N) for the communications signal streams 108(1)-108(S) that are orthogonal and spatially isolated from each other to serve multiple wireless client devices 106(1)-106(W) simultaneously. For example, the multiple beams 120(1)-120(N) may support multiple-input, multiple-output (MIMO) communications. The radio node 102 and MAA 114 are designed to support a maximum number of simultaneous beams 120(1)-120(N). The number of antenna elements 116(1)-116(E) in the MAA 114 dictates the maximum number of supported beams 120(1)-120(N) and shape of each and every beam. Radio signal processing resources in the radio node 102 can be shared to support the multiple service providers 104(1)-104(N). The capacity supported by the radio node 102 is split between the multiple service providers 104(1)-104(N). Beamforming can also be used to focus the beams 120(1)-120(N) to achieve increased communications range with increased signal quality by the reducing interference that results from spatial isolation with other beams 120(1)-120(N). For example, the communications system 100 in FIG. 1A that supports multiple service providers 104(1)-104(N) and beamforming may be deployed in a building environment 200 as shown in FIG. 2. The capacity of the communications system 100 can be increased and multiplied by the number of simultaneous beams 120(1)-120(N) provided with sufficient isolation. MAAs, especially for the sub 6 GHz frequency range, might capture a significant area. For example, a MAA for 3.5 GHz band may typically include thirty-two (32) to sixty-four (64) antenna elements with or without cross polarization arrangement at typical sizes of 13.4″×6.7″ and 26.8″×13.4″, respectively.
A drawback of using MAA can be the complexity, size, and cost of the antenna array and related electronic circuitry as well as higher power consumption. For example, as shown in FIG. 3, if a conventional fully digital beamforming arrangement is employed in the radio node 102 of the communications system 100 in FIG. 1A, every antenna element 116(1)-116(E) in the MAA 114 is coupled to a separate RF chain circuit 300(1)-300(E) that includes a dedicated downlink digital-to-analog (D/A) converter 302(1)-302(E), a downlink power RF amplifier circuit 304(1)-304(E), uplink analog-to-digital (A/D) converter 306(1)-306(E), an uplink RF amplifier circuit 308(1)-308(E) (e.g., a low noise amplifier (LNA)), a downlink transmitter circuit 310(1)-310(E), and an uplink receiver circuit 312(1)-312(E). For a sixty-four (64) antenna element MAA 114, this means that sixty-four (64) separate RF chain circuits 300(1)-300(E) must be provided, adding size and cost. Every communication signal provided through the RF chain circuits 300(1)-300(E) is processed individually by the radio node 102, thus adding processing complexity in the radio node 102.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.